Other Balance Sheet Accounts - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Net total of intangible assets	$ 1,300	$ 1,660
Patent application costs [Member]
Finite-Lived Intangible Assets [Line Items]
Total of summary of intangible assets	2,252	2,972
Accumulated amortization	$ (952)	$ (1,312)